Circuit breakers



April 9, 1940,. w. M. LEEDS ET AL 2,196,419

CIRCUIT BREAKERS Filed May 28, 1937 2 Sheets-Sheet 1 Fig.1

WITNESSES;

C". wwrw INVENTORS W/n fhmp M. Leeds, Enn/Io Orfens/ J Ben amin R Baker April 1940- w. M. LEEDS ET AL 2.196.419

CIRCUIT BREAKERS Fi led May 28, 1957 2 Sheets-Shet 2 WITNESSE 0 j) 6' M W/nfhrap Leedg Patented Apr. 9, 1940 UNITED STATES PATENT OFFICE Baker, Turtle Creek, inghouse Electric 4: Manufacturing Company, lastmrittlbnrgh, Pa., a corporation of Pennsyl- Application May 28, 1937, Serial No. 155,212

19 Claims.

This invention relates to circuit interrupters of the liquid immersed type and more particularly to improvements in operating mec for securing the rapid separation of the interrupterv usual arrangement, the force of the accelerating spring is weakest at the end of the contact opening stroke which may permit the moving contact structure to rebound at the end of the opening stroke and interfere with the arc extinguishing function of the breaker.

In recent years, various schemes have also been devised, particularly in breakers of the liquid immersed type, for positively circulating are extinguishing liquid within an arc rupturing chamher during the circuit interrupting operation. The means usually employed constitute a piston associated with the arc chamber and which is adapted to be actuated simultaneously with the moving contact structure. We have discovered that under certain conditions of operation the pressure within the arc chamber arising from the action of the are upon the liquid, is sumcient to materially slow down the liquid moving means, and in some instances stopping it entirely prior to the end of its stroke, thereby rendering the liquid circulating means ineffective. It is, of course, conceivable that the deleterious effect of the pressure within the arc chamber may be overcome by increasing the tension of the accelerating spring or springs.

This method of overcoming the difllculty merely introduces a further difllculty which, from a commercial point of view, is perhaps more objectionable than the former, since for every increase in the accelerating force by means of springs, a corresponding increase in force is required to rechargethe springs during the closing operation of the breaker. We have discovered that the pressure created by the are within the breaker casing may be utilized to assist the spring charged operating mechanism to accelerate both contact separation and oil circulation. By utilizing the pressure generated ,by the arc inthis manner,the tension of the accelerating spring may be materially decreased, thereby also reducing the force required for closing the breaker. It, therefore, follows that high speed opening. and closing may be effected with a minimum expenditure of power.

More directly stated, the objects of our invention are as follows: to improve the opening and closing performance of circuit interrupters of the liquid immersed type; to provide improve- 5 ments in the operating means of circuit interrupters of the liquid immersed type for securing a more rapid contact separation and a more positive circulation of arc extinguishing liquid within the arc chamber; to provide an improved mechal0 'nism for circuit interrupters of the liquid immersed type which utilizes the pressure generated by the arc to assist the mechanism in moving the contacts to open circuit position and circulating oil in the arc chamber against the pressure created by the arc; to provide an improved operating mechanism for liquid immersed breakers embodying means for utilizing the pressure generated by the arc to assist in the opening movement of the breaker, which mechanism per- 50 mits the actuation of the breaker contacts to open and closed positions under conditions of no load independently of the means utilizing the internal pressure of the breaker; to provide means utilizing the pressure generated by an arc to assist in the opening operation of a liquid immersed type breaker, which means are operative without substantial time lag irrespective of the position of the breaker contacts-between predetermined limits; and to provide a simplified strucgo tural arrangement whereby the above-named objects may be eflected in liquid immersed breakers employing a plurality of arc extinguishing devices connected in series.

Other objects and advantages relate'to details 5 of the structure and will appear more fully in the following description taken in connection.

with the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view showing a circuit interrupter embodying the improve- 40 ments of our invention;

Fig. 2 is a longitudinal sectional view through one of the arc extinguishing units employed in the circuit interrupter of our invention;

Fig. 3 is a fragmentary sectional view taken along the line III-III of Fig. 1, showing details of the contact structure when the interrupter is in the open circuit position; and

Fig. 4 is a cross-sectional view taken along the line Ill-IV of Fig. 1, showing the means for as-' so sisting the operating mechanism to actuate the interrupter to the open circuit position.

In the application of W. M. Leeds and Ennio Ortensi, Serial No. 145,273, filed concurrently herewith, now Patent No. 2,138,382 issued November 29, 1938, and assigned to the assignee of this application, a circuit interrupter of the liquid immersed type is shown and described, in which arc extinction is accomplished by means of a plurality of arc extinguishing units connected in series and arranged for tandem operation. Each of the arc extinguishing units in the above-named application comprises an arc chamber of narrow slot-like cross-section having an enlarged portion in which a pair of separable contacts are operative to establish an arc, and a restricted portion into which the arc is adapted to be moved just prior to current zero or at such time when the arc section has attained dimensions which permit easy entrance of the arc into the restricted portion. A piston member, which also carries the movable contact, is provided in each arc extinguishing unit for simultaneously establishing an arc and circulating arc extinguishing liquid into engagement with the arc.

Our invention is particularly adapted for use in connection with circuit interrupters of the type shown and described in the aforesaid application, to which reference may be made in describing the mode in which the instant invention may be carried out.

Referring to Fig. 1 of the drawings, the reference numeral 5 designates a cylindrical casing having an upper annular support plate 1, upon which is supported a cylindrical strain member 9 of insulating material, such as fibre or the like. The lowerend of the cylindrical strain member 9 is provided with a metallic flange I i which serves as a convenient means for bolting the member 9 to the support plate I. The upper vend of the cylindrical strain member 8 is provided with a metallic flange I3 to which may be bolted an annular support plate I5. Surrounding the cylindrical strain member 9 is a cylindrical member ll of insulating and weatherproof qualities, such as porcelain or the like. The weatherproof casing I! may be supported upon an annular subcasing i9 secured to the support plate I. A metallic flange member 2| secured to the lower edge 0! the weatherproof casing ll may be utilized in bolting the casing II to the support i9 as shown.

Interposed between the tops of the support plate I! and the weatherproof casing I I is a resilient expansion member 23, preierably of metal, and having a O-shaped cross-section. The expansion member 23 compensates for any inequality of expansion between the strain member 9 and the weatherproof casing l1, thereby maintaining the latter in compression. It will, of course, be understood that gaskets may be inserted as shown between the joints of the various members above described for the purpose'of preventing the leakage of liquid with which the in-. terrupter casing is filled.

The upper annular support plate I! is provided with a hanger plate II from which is suspended a plurality of, in this instance two, are extinguishing units 21. The are 21 are similar to those shown and described in the aforenamed application and are adapted to be assembled upon i'our tie rods II. only one of which is shown. The upper ends of the rods 2| have a threaded portion passing through. the hanger plate 25 for the reception of nuts 8|. In order to maintain the individual arc extinguishing units 21 in proper spaced relation with respect to each other and to the hanger plate ll, adjustable spacing sleeves 88 are provided surrounding the hanger rom ll.

units arcane Each 01 the arc extinguishing units, as more clearly shown in Fig. 2, comprises a plurality 01 plates of insulating material disposed between an upper end plate 35, preferably of metal, and a lower end plate 31, preferably of insulating material. The intermediate plates designated as at 3|, ll, 0, I, I! and I! each have a slot-like aperture therethrough to provide a relatively narrow arc chamber generallydesignated at ll. These latter plates are preferably of insulating material, such as fibre, and are also provided with a circular aperture joining one side of the slotlike apertures to provide a cylindrical passage 53, the purpose of which will appear more fully hereinaiter. The plates are provided with U- shaped inserts of magnetic material 58 disposed with their parallel elements on opposite of the slot-like passage 5| so as to provide means for moving an arc laterally within the passage.

The upper end plate 35 carries a movable contact member 51, which is resiliently mounted upon the guide and tensioning bolts 5!. The contact carrying member 51 has a stationary contact 6| secured thereto, which contact is adapted to extend through the end plate 3| into the arc passage II. The stationary contact ii is adapted to be engaged by a moving contact 63, which is carried by the contact support member 85. The support member 08 is provided with the tubular metallic coupling member 01 secured to the lower end thereof. The tubular coupling member 61 is provided with an upstanding rod 69 of insulating material having a metallic coupling H secured to the upper free end thereof. The rod 0! is adapted to support a piston 13 which is maintained in assembled position upon the rod 0 by means of nuts 15 screw threaded onto the metallic portion 1|.

The metallic coupling member I of the upper unit 21 is adapted to be joined to the metallic coupling member ll of the next lower unit 21, thereby connecting the two units electrically in series and at the same time coupling the contact carrying members II and the pistons 18 in'tandem for simultaneous actuation.

The coupling member II 01 the lower unit 21 is provided with yieldingly mounted contact nogers I adapted to engage a contact actuating member 19, which contact member is adapted to be actuated vertically in straight line motion by 'an actuating linkage generally designated at II. The lower end of contact actuating member H is provided with a guide member II which is adapted to be slidably received by a guide tube ll extending through and secured to the base of the casing I.

The metallic coupling 'll of the arc extinguishingunitl'lisprovidedwithacoaxiallyaligned v operating rod II, which rod extends upwardly through a cylindrical casing II. The casing II is supported and secured to a plate ll having a flange II which in turn rats upon the upper annular plate II. The upper end of the operatingrodl'lterminatesinaspringchamberlland is provided-with a guide member 01. Inter-posed between the guide member I! and the removable topplateilofthespringchamber llisanaccelcrating spring III. I

The moving contact assemblage. in c ordance with the ioregoing description, comprises the .gulde member or, operating rod .1, metallic couplingmemb'erllottheupperunitl'Ltheinsulatingrodlicarryingthecontactsupportll andthemnvablecontactllthemetalliccoupling" mcmbcrttwhichisiolnedtothemetamecoupling member II of the lower unit 21, which unit also has an insulating rod ll. contact carrying member 85 of the lower unit and its movable contact 63, the lower metallic coupling member 61 carrying contact fingers II in turn engaging the movable contact actuating member II. This assemblage also carries the pistons 13 disposed about the insulating rods 8!. Thus actuation of the operating linkage 8| will operate the movable contact assembly as a unitary structure to open and closed positions. During movement of the assemblage upwardly to the closed circuit position, the linkage 8| is required to overcome the bias of the accelerating spring IOI.

When in the closed circuit position, as shown in Fig. 1, the electrical circuit through the interrupter proceeds from the line terminal I" through the flexible connection I05, connection "II to the contact carrying member II of the upper unit 21,- contact 6|, movable contact I,

contact carrying member 65, coupling member 61, coupling member II of the lower unit 21, from whence the circuit proceeds through the lower unit 21 in like manner as the upper unit and 1 emerges at the contact fingers II and proceeds to the contact actuating member I9. The contact actuating member I! is provided with a flexible conductor I09, which is joined with a conductor III connected to the base of the casing 5 which may serve as the other line terminal of the interrupter.

Upon operating the interrupter to the open circuit position, the actuating mechanism of the interrupter (not shown) through the medium of an actuating red I ll operates the linkage 8| which in turn lowers the contact actuating member I9, thereby permitting the accelerating spring IIII to move the operating rod 81 and the entire movable contact assemblage of both are extinguishing units 21 to the open circuit position. The arc established between the stationary contact SI and the movable contact 3 of each unit will be moved laterally in the are e 5| onto the arc horns II! and III disposed in the upper and lower ends of the arc passage.

The products of decomposition of the are are permitted to escape from the passage 5| through a vent opening II! provided in the plates 35 and 39 of each arc extinguishing unit 21 which join the rearward end of the slots in the respective plates forming the passage II. Thus the pressure developed in each of the arc extinguishing units 21 resulting from the formation 01 the arc therein is communicated to the liquid contained within theenclosure defined by the cylindrical strain member 9.

When the arc has been moved onto the upper and lower arc horns H5 and III, respectively, thelectrical circuit through the two are extinguishing units proceeds from the upper contact carrying member 51 of the upper unit 21 to the metallic end plate 35, the upper arc horn H5 through the arc to the lower are born I", connection Hi to the upper plate 35 of the lower unit 21, through which it proceeds in a similar manner as for the upper unit 21, and emerges at a connection I23 which is in turnconnected to the contact flngersII.

During the opening movement of the movable contact 63, the action of piston II in the cylindrical passage 53 circulates arc extinguishing liquid contained within the passage into engagement with the are, thereby forcing the products of decomposition of the are from the arc passage substantially as rapidly as they are formed. The

arcpasagelLasmorespeciiicalLvdisclosedin the store-named application, has a configuration such that movement of the arc laterally toward the rearward portion of the passage 5| does not take place until the arc has a predetermined cross-sectional area. In other words, the arc is permitted to play in an enlarged portion of the passage in the region of the contacts 61 and 83 until its cross-sectional area has been reduced sufliciently to permit entrance into the restricted portion just prior to the current zero, whereupon it may readily be moved by the magnetic action of the U-shaped plates 55' into the constricted portion rearwardly of the passage 55. While in this constricted portion, the arc is subjected to a turbulent cross blast of the products of decomposition of the arc and also to the flow of oil resulting from the action of the piston II. The turbulent intermixing of un-ionized gas and oil particles with the arc while being thus confined subjects the arc stream to a rapid cleion-' 21. The contact actuating member I9, however,

is free to continue its downward movement for a predetermined distance, causing the contact lingers It to be disengaged therefrom to thereby introduce an additional gap in the circuit, as

shown in Fig. 3.

It will be noted that the formation of the er in the passage II of each unit 21 may produce considerable pressure, which would ordinarily react on the lower exposed face of the support member I of the piston I3, thereby tending to retard the opening movement of the contacts I. In order to overcome the retardation of the moving contacts 63 during the opening operation and also to increase the speed of separation of the contacts even though a relatively low tension accelerating spring III is used, we have provided an accelerating device that utilizes the pressure communicated from each unit 21 to the enclosure defined by the cylindrical strain member 9. x

The upper end of the. strain member 9 is substantially enclosed by the support plate SI and the cylidrical chamber 89. Within the cylindrical chamber 89, is provided a movable piston or baiile member I25 which in turn is carried by a tubular member I21 extending therethrough in coaxial alignment therewith. The tubular member I 21 has an enlarged annular cross-sectional or piston portion I29 extending above the bailie I 25, and is adapted for sliding movement in an inner cylindrical casing I3I. The upper ends of the coaxially disposed cylindrical casings 89 and HI are, respectively enclosed by the plate supporting the spring housing 95. The operating rod 81 is provided with a piston I33 rigidly secured thereto and slidably operative in the bore of the tubular piston I29. The baiile member I25 and its cooperating tubular piston member I29 are biased downwardly by a spring I35 encircling the inner casing I3I, so that the lower end of the tubular member I21 normally rests upon the hanger plate 25.

Y The side walls of the cylindrical casing 89 are provided with a series of graded vent open- 7 ings or apertures as indicated at I31. These vent openings are positioned adjacent and immediately above the baflie member I25 when the baffle is in its normal position, as shown in Fig. 1, and have successively increasing areas in the upward direction. The inner cylindrical casing I3I is also provided with a series of apertures of vent openings, in this instance preferably in the form of segmental circumferential slots, and shown at I39. The vent openings I39 are positioned just above the upper edge of the tubular piston I29 when the piston is in its normal position as shown.

A cylindrical casing I III is preferably sealed at its lower end to the annular support plate I5 and extends upwardly beyond the cylindrical chamhers 89 and I3I so that these chambers may be completely submerged in arc extinguishing liquid. A hood I42 bolted to a flange I of the casing I40 encloses the upper end of the circuit interrupter housing.

From the foregoing description, it follows that as the operating rod 8'! is moved downwardly during the circuit opening operation carrying with it piston I33, liquid will be drawn in through the apertures I39 to maintain the inner casing I3I filled with liquid. As soon as the pressure resulting from the arcs within the interrupting units 21 builds up within the tubular strain member 9, this pressure will react upon the baffle member I25, which is free to move vertically within the outer cylindrical casing 39, to thereby actuate the tubular piston I29 upwardly, which seals the apertures I39 and subjects the liquid within the inner cylindrical casing I3I to pressure, which pressure reacts downwardly upon the piston I33 to assist the operating rod 31 to move the contacts 53 to the open position and to force the piston I3 against the pressure set up within the arc passages 5I.. Movement of the baIIle member I25 upwardly also uncovers the vent openings I31 through the side walls of the cylindrical chamber 89 to thereby relieve the pressure within the casing 3.

As soon as the pressure subsides within the casing 9 following the interruption of the circuit, biasing spring I35 assisted by gravity again returns the baffle member I25 and its associated tubular piston I29 to the normal position. In this position, the ports or vents I39 are again uncovered, and operating rod "with its piston I33 are free to be moved vertically in order to return the interrupter to the closed circuitposition. It will thus be seen that the movable contacts with their associated pistons 13 are free to be moved to the open and closed circuit'podtion independently of the baffle member I25.

It should also be noted that the particular arrangement described permits the baille member I25 to become effective in assisting the opening movement of the interrupter contacts at any point in the opening stroke without appreciable time delay following the creation of pressure within the casing 9. In other words. the force resulting from the pressure within the are passages 5I of the units 21, communicated to the liquid in the casing 9 and acting upon the baflie I25 is transmitted through hydraulic forcemultiplying means to the operating rod 31.

permits the effective operation of the bafllemember I25 without time delay in the on of force to the operating member 31.

The ratchet action will be apparent upon noting that when the baffle I2! is in the lowermost position, as shown in Fig. 1, the ports I35 are opened, thus permitting the actuating member 31 and the attached piston I35 to move downwardly and to draw liquid through the ports I39 to maintain the casing I3I filled with liquid. As long as the pressure within the casing 9 is insufficient to raise the baffle I25, the ports I39 will remain open and the hydraulic connection between the bafiie and the operating rod 31 will remain ineifective. In the event of a time delay in the building up of pressure within the casing 9, the operating rod 81 may move an appreciable distance before the baflle I25 is raised suf-,

ficiently to close the ports I39. For example, the operating rod 81 may have moved half away to the open circuit position prior to movement of the bailie I25 and the closing of the ports I 33. As soon as the ports I39 are closed, a further movement of the bafiie I25 in the upper direction immediately subjects the liquid within the casing I3I to pressure from the action of piston I29 carried by the bailie I25, since the casing I3I is always maintained filled with liquid. This resultant pressure within the casing I3I then reacts upon the piston I35 to assist in moving the contacts 53 to their open circuit position during the remaining portion of the opening stroke. It is, therefore, apparent that the bafile I25 may become. operatively coupled to the operating rod 31 at any time during the opening operation of the interrupter. Since this hydraulicr coupling between the baiiie I25 and the operating rod 31 resembles a mechanical ratchet in action, it may properly be called a hydraulic ratchet.

It is also to be noted that the hydraulic coupling between baffle I25 and the operating rod 31 becomes effective substantially as soon as the baiile is actuated by the pressure within the easing 3, and this is so irrespective of the position of the operating rod 31 between predetermined limits which are fully set forth hereinafter. In other words, there is no lost motion between the baflle I25 and the operating rod 31 once the ports I39 are closed. This absence of lost motion, therefore, permits the baffle I25 to become effective in assisting the opening movement of the contact 33 without appreciable time delay following the creation of pressure within the casing 3.

It will be observed that the lower or effective area of the baille member I25 is large as compared to the upper or effective area of the tubular piston I29. The effective area of the baffle I25 is also large as compared to the effective areas of the piston I35 and the pistons I3 within the arc es 5|. The difference in these areas makes it pomble to utilizethe relatively low pressure within the casing 9 to comferact the reactive forces upon the pistons 13 due to a relatively higher pressure within the arc passage 5| of each arc extinguishing unit 21. By properly selecting the areas of the several pistons, it is possible to substantially completely te the reactive forces operating upon .thepistonllduetothepressurewithinthearc passages 5|, so that the accelerating spring IOI need only supply a force sufficient to overcome the inertia and friction of the moving parts and the frictional resistance of the liquid flow. It

. is also possible to proportion the respective areas when overcompensation is obtained of the reactive pressure acting upon the pistons ll, it is apparent that the hydraulic system including the arc extinguishing liquid, bailie Ill, pistons I29 and I35 and their associated casings constitute a hydraulic iorce multiplying means since a force is obtained tending to move the pistons 13 to the open circuit position that is greater than the force-tending to oppose the opening movement.

From the foregoing, it follows that the areas of the pistons may also be proportioned so as to only partially compensate the effect of the reactons I9. However, in practice overcompensation is more desirable where a high contact accelera-' their full open position. The delayed upward movement of the baflle I25 under these circumstances immediately seals the ports I" prior to uncovering oi the ports I31. Therefore, unless further provision is made to relieve the pressure within the inner cylindrical casing I3I, further upward movement of the baflle I25 is prevented which may result in building up pressure within the casing 9 to a dangerously high value. In order to relieve thepressure within the cylindrical casing I3I at the end of the opening stroke, we have provided vents or notches I in the operating rod 91 adjacent theguide member 91. These notches permit the relief of pressure from within the casing I3I to the spring chamber 95. Thus a relief of pressure in the inner chamber I3I permits the bailie I25 to be raised and relieve the pressure within the casing 9 through the ports I31.

It may also occur that during the closing operation of the interrupter during conditions of load that an arc may be established between the contacts prior to the complete closing of these contacts which may build up sumcient pressure within the casing 9 to raise the baiiie I25, thereby sealing oi! the openings I39 and stall the piston I33 and its operating rod 8'1, thereby preventing the completion of the closing stroke. Thus an arc may be maintained for a period of time sufllcient to cause a pressure within the easing 9 high enough to injure the interrupter casing. In order to avoid this injurious efle'ct, we have provided a second series of openings or notcheson the operating rod 91 located as indicated at I43. The notches I" are so positioned with respect to the upper wall at 99 of the inner casing III that the pressure within the latter casing is relieved just before the contacts OI and 83 make engagement with each other. The notches I" are, however, so arranged that upon final movement of the contacts 53 to the fully closed position, the enclosure within the casing I3I is again sealed, thereby preventing further movement of the baiiie in the upward direction which might put it in the uppermost position of its path of travel and render it useless in the event that it were called upon to operate in an immediate interrupting operation following the closing of the breaker contacts.

From the foregoing description, it follows that the interrupter contacts may bemoved to the open position irrespective of the pressure conditions within the casing 9. Movement of the contact structure to the closed circuit position is prevented as long as suflicient pressure exists in the casing 9 to maintain the baflle I25 raised and the ports I39 closed. However, since the pressure within the casing 9 is quickly dissipated through the vent openings I31, the-baiiie I25 is.

lowered promptly by the joint action of gravity and the spring I35 to its normal position so as to again uncover the ports I39 thereby permitting free movement of the operating rod 81 to the closed circuit position. tive force opposing opening movement of the pis- Although we have shown and described a specific circuit interrupter structure, utilizing a particular arrangement responsive to the pressure within the circuit interrupter casing for assisting the operating mechanism during the opening operation of the interrupter, it is to be understood that the same is for the purpose of illustration and that changes and modifications may be made by those skilled in the art without departing We claim as our invention:

1. In a circuit interrupter, a casing containing arc extinguishing liquid, separable contacts within said liquid, means for operating said contacts to open and closed positions, and means responsive to the pressure within said casing to assist said operating means to separate said contacts, and a fluid force-transmitting means between said pressure responsive means and said operating means for transmitting a force to saidoperating means with substantially no time lag irrespective of the position of said operating means within predetermined limits.

2. In a circuit interrupter, a casing containing arc extinguishing liquid, separable contacts within said liquid, means for operating said contacts to open and closed positions, a piston in said casing movable in response to pressure within the casing to assist said operating means to separate said contacts, and a hydraulic forcetransmitting device between said piston and said operating means for transmitting a force to said operating means without substantial time lag for all positions of said operating means between predetermined limits.

3. In a circuit interrupter, a. casing containing arc extinguishing liquid, a pair of contacts sub merged in said liquid at least one of which is movable to open and closed positions, an operating member for actuating said movable contact to establish an arc, a bafile member within said casing movable in response to pressure within the casing produced by said arc, a cylindrical enclosure within said casing having a fluid connection therewith for maintaining said cylindrical enclosure filled with liquid, a piston movable within said cylindrical enclosure mechanically coupled to said baiile member and adapted to be actuated thereby for subjecting the liquid within the cylindrical enclosure to pressure, and pressure responsive means mechanically coupled to said operating member movable in response'to pressure created within said cylindrical enclosure to assist in moving said movable contact to the from the spirit and scope of the appended claims.

to establish an arc, a baiiie member within said casing movable in response to pressure within the casing produced by said are, a cylindrical enclosure within said casing having a fluid connection therewith for maintaining said cylindrical 1 enclosure filled with liquid, a piston movable 5. In a circuit interrupter, a casing containing I are extinguishing liquid, a pair of contacts submerged in said liquid at least one of which is movable to open and closed positions, an operating member for actuating said movable contact to establish an are, a baiiie member within said casing movable in response to pressure within the casing produced by said are, a cylindrical enclosure within said casing having a fluid connection therewith for maintaining said cylindrical enclosure filled with liquid, a piston movable within said cylindrical enclosure mechanically coupled to said baflie member and adapted to be actuated thereby for subjecting the liquid within the cylindrical enclosure to pressure, and a second piston within said cylindrical enclosure movable with said operating member, said second piston being responsive to pressure created within said cylindrical enclosure in response to movement of,.said baflle member to assist in moving said movable contact to the open circuit position.

6. In a circuit interrupter, a casing containing arc extinguishing liquid, a pair of contacts submerged in said liquid at least one of which is movable to open and closed positions, an operating member for actuating said movable contact to establish an arc, a baflie member within said casing movable in response to pressure within the casing produced by said arc, a cylindrical enclosure within said casing having a fluid connection therewith for maintaining said cylindrical enclosure fllled with liquid, a piston movable within said cylindrical enclosure mechanically coupled to said baflie member and adapted to be actuated thereby for subjecting the liquid within the cylindrical enclosure to pressure, a

second piston within said cylindrical enclosure movable with said operating member, said second piston being responsive to pressure created within said cylindrical enclosure in response to movement of said bame member to assist in moving said movable contact to the open circuit pomtion, and means operative in accordance with predetermined movement of said operating member to relieve the pressure within said cylindrical enclosure to enable said operating member to be moved independently of said baiile member.

7. In a circuit interrupter, a casing containing arc extinguishing liquid, a pair oi contacts submerged in said liquid at least one of which is movable to open and closed positions, an operating member toractuating said movable contact to establish an are, a baiiie member within said casing movable in response to pressure within the casing produced by said are, a cylindrical enclosure within said casing having a fluid connection therewith for maintaining said cylindrical enclosure fllled with liquid, a piston movable within said cylindrical enclosure mechanically are e coupled to'said bails member and adapted to be actuated thereby- !or subjecting the liquid within the cylindrical enclosure to pressure, a second piston within said cylindrical enclosure movable with said operating member, said second piston being responsive to pressure created within said cylindrical enclosure in response to movement of said baflie member to assist in moving,

said movable contact to the open circuit position, the flow of liquid through said fluid connection being controlled in accordance with predetermined movement of said flrst piston for making said second piston operative to assist said operating member in moving said movable contact to the open circuit pomtion irrespective of the position of said operating member within predetermined limits.

8. In a circuit interrupter, a casing containing arc extinguishing liquid, separable contacts for establishing an are within said liquid, movable means for positively moving a quantity of said liquid into engagement with said are, operating means ior actuating said movable means, pressure responsive means movable in response to the pressure within said casing, and a fluid coupling between said pressure responsive means and said operating means for transmitting a force to said operating means to assist in moving said quantity of liquid. I

9. In a circuit interrupter, a casing containing arc liquid, separable contacts for establishing an are within said liquid, movable means for positively moving a quantity oi said liquid into engagement with said are, operating means for actuating said movable means, and means raponsive to the pressure within said of the position of said operating means between predetermined limits, said movable means being operative independently of said pressure responsive means.

10. In a circuit interrupter, acasing containing liquid, separable contacts for establishing an are within said liquid, 9. piston in said casing for positively moving a quantity of liquid into engagement with said arc, operating a second piston in said means to assist in moving saidflrst pistonagainst the pressure within said casing.

11. In a circuit interrupter, a casing containing arc extinguishing liquid, separable contacts ior establishing an are within said liquid, a piston in said casing for positively moving a quantity of liquid into engagement with said are, operating means for said piston, a second piston in said casing movable in response to pressure within the casing. and a coupling device between said second piston and said operating means for transmitting a force to said operating means without substantial time lag for all positions of said operating means between predetermined limits.

12. In a circuit interrupter, a casing containing are e liquid, means deflning an arc chamber submerged in said liquid, said chamber having a fluid connection with said casing. separable contacts for establishing an are within said are chamber, a piston for circulating liquid within said chamber, operating means for actu- Ming said piston, a second piston within said moans casingmovableinresponsetopressurewithin are extinguishing liquid, a pair of contacts within saidliquidatleastoneotwhichismovableto break the circuit to thereby establish an arc and create pressure within the casing, a piston within said casing tor moving a quantity oi liquid into engagement with said are, common operating means for said movable contact and said piston, means'responsive to the pressure within said casing for transmitting force to said operating means to accelerate the opening movement of said movable contact and to assist said pistonv in moving liquid against the pressure withinsaid casing.andailuidactnatedcoupling betweensaid pressm'eresponsivemeamandsai operating means.

14. In a circuit interrupter, a casing containing arc extinguishing liquid, a plurality of are extinguishing devices submerged in said liquid.

each of said devices including an arc chamber having a fluid connection with said casing,apairoi'contactswithineachotsaid chambersatlcastoneoiwhichismovableto open and closed positions, a common operating member for simultaneously actuating-said-movablecontactstoestablishanarcwithineach arc chamber and to thereby create pressln'e 'withinsaidc asingapistoni'oreacharcexdeviceadaptedtobeactuatedsimultaneously with said movable contact by said operatingmembertociroulateliquidwithineach ofsaidarcchammabaflemembermovabie withinsatdcasinginresponsetothepressure createdbysaidarcs,andaiorce-multiplying connectionbetweensaidbailememberandsaid operatingmembertortransmittingai'orceto saidoperatingmemberdurlngtheopeningmove mentotsaid movable contacts, said force-multiplyingconnectlonenablingsaidmovablecontacts tobemo'vedtotheclosedcircuitpositlonirrespective o! the pressure conditions in said l5. maclrcuit interrupter,acasing containing arcliquid.apluralityoi'arcexdevices submerged in mid liquid. each of said devices including all arm chamber having a fluid connection with said casing. a pairofcontactswithineachoi'saidchambersat least once! which is movable to open closedpositions.aoperatingmemberior iorces exerted upon said pistons by the respective positionandreleasable coupling meansbe tween said movable means and said operating a force irom said baflie member to said operating member with substantially no time lag irrespective of the position oi said operating member within predetermined limits to assist saidspring biasing means in moving said operating member to theopen circuit position.

16. In a circuit interrupter, a casing containing arc extinguishing liquid, a plurality of arc extinguishing devices submerged in said liquid, each of said devices including an arc chamber having a iiuid connection with said casing, a pair of contacts within each of said chambers at least one of which'is movable to open and closed positions, a common operating member for simultaneously actuating said movable contacts to establish an are within each arc chamber and to thereby create pressure within said casing, a

piston for each arc extinguishing device adapted to be actuated simultaneously with said movable contact by said operating member to circulate liquid within each oi said are chambers, and means responsive to pressure within said We created by said arcs for transmitting a force to said operating member that is greater than the tive pressures within said arm chambers to assist movement of said operating member to the open circuit position.

- 17. In a circuit interrupter. a casing containing are extinguishing liquid, separable contacts within said liquid, means for operating said contacts to open and closed position, movable means operative in response to within saidcasing, and a iiuid actuated coupling means between said vmovable means and said operative means, normally inoperative to permit movementot said operating means independently of said movable means, and automatically made operative in response to pressure within said casing to cause said movable means to be coupled with said operating means to assist the latter in moving the contacts to open circuit position.

18. In a circuit interrupter, a casing containing arc extinguishing liquid, separable-contacts within said liquid, means for operating said contacts to open and closed position, a piston movable in response topressure withinsaid casing, a fluid actuated coimling between said piston and said operating means for transmitting a force to said operatingmeans in a direction to assist in -opening said contacts, said couplingpeing P- erative only in response to pred pressure conditions within said casing.

19. In a circuit interrupter, a casing containing arc extinguishing liquid, separable contacts with insaidliquid,means tor operatingsaidcontacts to open and closed position, movable means operativeinresponsetopressurewithinsaidcasing, meanshiasingsaidmovablemeanstoaninoperameanstor transmitting a force from said movgabiemeans'tosaidoperatingmeanasaidcoupling mean'sbeinginoperativewhensaidmovable -meansisinsaidinoperativeposition,and

renderedoperativeinresponsetomovement at said movable means.

Wm? H. LIIDB. sumo on'rmsr. mm P. mm. 

